1. Field of the Invention
This invention relates to batteries. More particularly, this invention relates to batteries having a non-aqueous electrolyte, an alkali metal anode and a cathode comprising a compound of carbon with fluorine and a Lewis acid as a cathode-active material.
2. Description of the Prior Art
Batteries have been widely used for many years. Generally their use is limited because of their low energy output per unit weight. Recently, interest has grown in attempting to develop nonaqueous high energy batteries which are capable of being discharged or recharged over many cycles.
Among the battery systems currently receiving intensive investigation are those which have lithium as the anode and intercalation compounds of graphite and fluorine as the cathode-active material. See, for example, Hunder, H. F., et al, "J. Electchem. Soc." 120, 1161 (1973).
Another nonaqueous battery baving a lithium anode and a lamellar graphite cathode is disclosed in U.S. Pat. No. 3,844,837. Specifically, the cathodic depolarizer of that battery is a compound formed by reacting pyrolytic graphite with certain lithium salts by impressing an electric current between a lithium anode and a pyrolytic graphite cathode immersed in a solution of the salt in an organic solvent. There are some serious limitations, however, on the use of such cells. The electrointercalation of the graphite will not result in a fully intercalated product. As a result thereof, the cathode is, to a large extent, graphite itself. Moreover, the cathode is subject to rapid disintegration as a result of expansion and contraction of the graphite during charge/discharge cycles. Additionally, since the intercalated anion is inserted in the lamellar graphite spacings mainly near the surface of the graphite, the anion apparently readily diffuses to the anode thereby discharging the cell internally.
Another nonaqueous battery that should be mentioned is that disclosed in U.S. Pat. No. 3,990,915. The cathode of that battery is formed by reacting crystalline carbon with an interhalogen fluoride in the presence of hydrogen fluoride.